Steel rail



Patented Mar. 6, 1928.

UNITED STATES PATENT. OFFICE,

- STEEL No Drawing. Application filed September 26,

In railway technics great progress has been made in the last decades as regards the construction of locomotives and cars. The continually increasing demands concerning the tractive power of the locomotives and the greater carrying capacity of the cars have been compensated by a corresponding increase of the wheel pressure. The improvements made in the construction and quality of the track and the rails, have not been equal to the progress in the construction of the locomotives and the cars. The

. rail profiles have been enlarged practically ,in accordance with the higher wheel pressure and the increasing speeds, but the material ofthe rails, viz: the rail steel, has 'not been essentially changed, thereby'imposing a strong wear and tear on the rails and reducing their life-time, especially on lines with curves of a comparatively short radius and a steep down-grade. There have been employed for such lines rails with a particularly great resistance to tensile stress, but it has been discovered after a short time of service that the tensile strength has practically nothing to do'with the resistance to wear in that experience showed that rails with a great'tensile strength were subject to greater wear and tear than-rails with a smaller tensile strength.

Ordinary rail steel is so produced as to contain about from 0.4 to 0.45% of carbon and about from 0.8 to 1% 'otmanganese,

and in man cases an addition of about 0.15% of silicium is made in order to increase the density of the steel. It is well known that siliciumrenders the steel more resistant to wear, and in view of this fact rails have been manufactured having a greater percentage of silicium than above stated, but no change was made in the percentage of the carbon and the manganese. A higher percentage of silicium than 0.25, has, as a rule, not been made use of for reasons connected with the rolling of the steel,

-the tact being that steel having a higher percentage of silicium is likely to become rent when being rolled.

The present nvention relates to a steel having a higher percentageof silicium viz.

from 0.25% to 0.50% and eing able to stand easily the heat of the heating furnace and in proportion That it is proper to decrease the percentage of the carbon when the percentage of the silicium is increased in order to prevent the steel from becoming brittle will become obvious from the following consideration:

The three hardness-producing substances C, Si and Mn, of which C is the most efi'ective, render the steel more hard and brittle to the increase of their percentage in it. Now, to prevent the surpassing of a certain limit as regards the hard ness and the brittleness (that limit being determined by the impact test when the rails are being taken over), the amount of one 0 these hardness-producing substances (C according to this invention) must be diminished when another of those substances (Si according to this invention) is enhanced, the amount of-the third substance remaining as it was or being increased in a certain suitable measure.

Now, as the high percentage of Si on the one side and the high percentage of Mn on the other side increase the resistance to wear of the steel, this silicium-manganese steel forms a rail steel in which greatest resistance to wear and tear is combined 'with greatest toughness, both in natural state,

that is to say, no subsequent heat treatment 1925, Serial No. 58,938, and in Germany October-'9, 1924. v

"tostand the otlicially prescribed impact test. v

As a new article bf manufacture a steel rail having a content of manganese, amounting to from 1 4% to 2%, a content of silicium amounting to from 0.25% to 0.50% and a content of carbon amounting to from 0.20% to 0.45%, said contents of silicium and carbon ranging inversely or approximately inversely relatively to each other.

In testimony'whereof ture.

/ H RMAN G 

